Prosecutors have outlined their case against the gunman who shot dead 12 people at a US premiere of the latest Batman film.
The hearing, the first extensive public disclosure of the attack's details, will determine whether the case will go to trial.
James Holmes is charged with more than 160 counts in the Colorado attack, including murder and attempted murder. Investigators say he was wearing body armour and a gas mask when he tossed two gas canisters and opened fire in the cinema on July 20.
In addition to the 12 dead, 58 were wounded.
Details of the case have been kept quiet. Three days after the shooting, District Judge William Sylvester banned lawyers and investigators from discussing the case publicly, and many court documents have been kept secret.
Police say Holmes, now 25, had stockpiled weapons, ammunition, explosives and body armour. He was a first-year student in a Ph.D. neuroscience program at the University of Colorado, Denver, but he failed a year-end exam and withdrew. The shootings came six weeks later.
Holmes entered the cinema with a ticket and is believed to have propped open a door, slipped out to his car and returned with his weapons. Police arrested him outside the theatre shortly after the shootings ended.
Legal analysts said that evidence appears to be so strong that Holmes may accept a plea agreement before trial. In general, plea agreements help prosecutors avoid costly trials, give the accused a lesser sentence like life in prison rather than the death penalty and spare the victims and their families from the trauma of going through a lengthy trial.
Holmes' mental health could be a significant issue in the hearing. His lawyers have told the judge Holmes is mentally ill, but they have not said whether they plan to employ an insanity defence. He had seen a university psychiatrist, and apparently tried to call the psychiatrist nine minutes before the killing began.
Defence lawyers have said they plan to call at least two witnesses who could testify about Holmes' mental health. Prosecutors asked the judge to block the witnesses, but he refused.